1. Field of the Invention
The present invention relates to a power device for driving a motor mounted on a hybrid car or an electric car and causing a vehicle to run.
2. Description of the Related Art
An automobile such as an electric car running by means of an electric motor or a hybrid car running by means of both an electric motor and an engine mounts a power device accommodating a battery in a case. The power device causes the automobile to run by means of an electric motor. In order to increase an output, therefore, a large number of batteries are connected in series, thereby raising an output voltage. For example, a voltage of an electrical battery to be mounted on an automobile is 12V with few exceptions, and the output voltage of the power device for driving a motor for running is generally 200V or more, which is very high.
In a typical hybrid car on the market, an electric motor output is several tens kW and an output voltage of a power device is set to be 200 to 300V. The power device is designed to be resistant to a high power. Therefore, if an automobile is broken due to a car crash so that a short circuit is caused in an inner part, a very large current flows, which may cause a car fire. In order to prevent this bad effect, a power device has been developed for controlling a state in which an automobile is broken due to a crash.